1. Field of the Invention
The present invention relates to an object, a method, or a manufacturing method. Further, the present invention relates to a process, a machine, manufacture, or a composition of matter. One embodiment of the present invention relates to a semiconductor device, a display device, a light-emitting device, an electronic device, a manufacturing method thereof, or a driving method thereof. Specifically, one embodiment of the present invention relates to, for example, a semiconductor device using an oxide semiconductor and a method for manufacturing the same. Furthermore, one embodiment of the present invention relates to, for example, an etchant which can be used for a semiconductor device using an oxide semiconductor.
Note that in this specification, a semiconductor device refers to a semiconductor element itself or a device including a semiconductor element. As an example of such a semiconductor element, for example, a transistor (a thin film transistor and the like) can be given. In addition, a display device such as a liquid crystal display device includes a semiconductor device in some cases.
2. Description of the Related Art
There is a trend in a display device using a transistor (e.g., a liquid crystal panel and an organic EL panel) toward a larger screen. As the screen size becomes larger, in the case of a display device using an active element such as a transistor, a voltage applied to an element varies depending on the position of a wiring which is connected to the element due to wiring resistance, which cause a problem of deterioration of display quality such as display unevenness and a defect in grayscale.
Conventionally, an aluminum film has been widely used as a material used for the wiring, the signal line, or the like; moreover, research and development of using a copper film as a material is extensively conducted to further reduce resistance. However, the copper film has poor adhesion to a base film. In addition, diffusion of a copper element in the copper film into a semiconductor layer of a transistor causes degradation in characteristics of the transistor. Note that a silicon-based semiconductor material is widely known as a material for a semiconductor thin film applicable to a transistor, and as another material, an oxide semiconductor has attracted attention (see Patent Document 1).
Furthermore, as a method for manufacturing an array substrate for a TFT-LCD, an etchant containing at least one selected from neutral salt, inorganic acid, and organic acid in addition to hydrogen peroxide which can collectively etch a double metal layer including copper is disclosed (see Patent Document 2).